József SZABÓ¹, Róbert VASS² & Csaba TÓTH^1
1Universctiy of Debrecen, Department of Physical Geography and Geoinformatics, Egyetem tér 1., 4032, Debrecen, Hungary, e-mail: szabo.jozsef@science.unideb.hu, toth.csaba@science.unideb.hu
²Universctiy of Debrecen, Department of Meteorology, Egyetem tér 1., 4032, Debrecen, Hungary, e-mail: vass.robert80@gmail.com

EXAMINATION OF FLUVIAL DEVELOPMENT ON STUDY AREAS OF UPPER-TISZA REGION

Full text

Purpose of recent study is to show the fluvial evolution of the Upper-Tisza region on two study areas. In the Bereg Plain (from the border to the mouth of the Szamos) studying the deeply cut shore wall of the Tisza – partly due to meander cuts – together with the morphometric analyses of floodplain deposits and abandoned river beds yield information on the characteristics and pattern of natural accumulation. These indicate that the characteristics and pattern of recent sedimentation are determined primarily by the distance from active river beds. Characteristic feature of the youngest period is the accelerated accumulation rates (0.2-1cm/year) on the floodplains bordered by dams. These rates were determined by digital elevation models (DEMs); shallow boreholes and geodesical measurements. The part of the Tisza floodplain directly above the Tokaj gate (Bodrogzug) is special primarily because no flood preventing dams were constructed between the Tisza and the Bodrog thus the area remained a quasi natural fluvial development area free of intense cultivation up to now. The area is especially rich in forms characteristic for floodplains of the Great Hungarian Plain (abandoned river beds, levees, point bars, crescent beds, floodplain flats, etc.) annual (or even more frequent) flooding of which enable fluvial accumulation even today. Sedimentary analyses carried out with the help of drillings and in situ sediment traps show that accumulated sediments become finer gradually. Grain-size distribution of the sediment is depends on the distance of present (active) and abandoned river beds. Sediments from active beds and levees are coarse grained, while on floodplain flats are fine grained.